Mirai Nikki Future Diary follows the struggles of Yukiteru Amano, a 14-year-old lonely and introverted boy who observes life and jots down the events on his cell phone. However, his mundane life soon changes when Deus Ex Machina, the God of Time and Space, grants Yukiteru a "Random Diary," which shows highly descriptive entries based on the future and forces him into a bloody battle royale with 11 other holders of similarly powerful future diaries. With the last person standing designated as the new God of Time and Space, Yukiteru must find and kill the other 11 in order to survive. He reluctantly teams up with his obsessive stalker Yuno Gasai (who also possesses such a diary), and she takes it upon herself to ensure his safety.
Yukiteru soon learns that Deus is not what he seems, and his attempts to unravel the mysteries of his new existence lead him closer to the dark secrets behind Deus Ex Machina's plan. With the other diary holders, deadly games and an unexpected turn of events, the battle for survival and to become the new God of Time and Space is on. Will Yukiteru be able to survive and win the game, or will he succumb to the other diary holders and their deadly fates?